1. Field of the Invention
The technical field of the disclosed invention relates to a semiconductor device and a method for manufacturing the semiconductor device.
2. Description of the Related Art
There are a wide variety of metal oxides and such material oxides are used for various applications. An indium oxide is a well-known material and is used as a transparent electrode material which is necessary for liquid crystal displays and the like.
Some metal oxides have semiconductor characteristics. The examples of such metal oxides having semiconductor characteristics are a tungsten oxide, a tin oxide, an indium oxide, a zinc oxide, and the like. A thin film transistor in which a channel formation region is formed using such metal oxides having semiconductor characteristics is known (for example, see Patent Documents 1 to 4 and Non-Patent Document 1 and the like).
As metal oxides, multi-component oxides as well as single-component oxides are known. For example, homologous compound, InGaO3(ZnO)m (m is natural number) is known as a multi-component oxide containing In, Ga and Zn (for example, see Non-Patent Documents 2 to 4 and the like).
Furthermore, it is confirmed that an oxide semiconductor including such an In—Ga—Zn-based oxide is applicable to a channel layer of a thin film transistor (for example, see Patent Document 5, Non-Patent Documents 5 and 6, and the like).